462 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



range; key to the included species). — Gisl^.n, Ark. Zool., vol. 19, No. 32, 1928, p. 12; Kungl. 

 Fysiogr. Siillsk. Haudl., new sur., vol. 45, No. U, 1934, pp. 18, 20. 

 Caryometra (not of A. H. Clark, 1936) A. 11. Clauk, John Murray Exped. 1933-34, Sci. Reports, 

 vol. 4, No. 4, 1937, pp. 96, 103. 



Diagnosis. — A genus of Peromctrinae in wliich the elements of the IBr series and 

 the first 2 brachials have smooth and straight borders and are laterally in close oppo- 

 sition with their neighbors and sharply flattened against them; the synarthrial tubercles 

 are very prominent, sometimes extravagantly developed; and P» may or may not be 

 present. There are 10 to 1 5 or more arms up to 90 mm. in length. [Note by A.M.C.]. 

 In the specimens belonging to this genus which I have examined, the cirrus sockets 

 have the form of a boss sunken into a hollow in the centrodorsal (see figs. 19,aand 21, a 

 pp. 463 and 471). 



Type species. — Antedon diomedeae A. H. Clark, 1907. 



Oeoijraphical range. — From Madagascar to the Maldive and Kei Islands and 

 southern Japan. 



Bathymetrical range. — From 71 to 256 (?278) meters. 



Thermal range.— From 11.61° C. to 20.39° C. 



[Note by A.M.C] I have added Caryometra rohusta A. H. Clark, from off the 

 Maldive Islands, to this genus. Apart from having only 10 arms it has great simi- 

 larity to P. afra. This is discussed further on page 470. 



KEY TO THE SPECIES OF PEROMETRA 



[by A.M.C] 



o'. More than 10 arms (northeast of Madagascar; 228 meters) afra (p. 462). 



a'. 10 arms. 



6'. The outer segments of Pi not expanded and spinous at their distal ends (fig. 20,a, p. 465). 

 c'. P, usually absent; the longest cirri about equal to one third of the arm length (Southern 



Japan; 71-254 [?278] meters) diomedeae (p. 464) 



c". P, present; the longest cirri about one fifth of the arm length (Kei Islands; 256 meters). 



pusilla (p. 469) 



6*. The outer segments of Pi conspicuously flared and spinous (fig. 21, c, p. 471) (off the Maldive 



Islands ; 229 meters) robusta (p. 470) 



PEROMETRA AFRA A. H. Clark 



Figure 19 



Perometra a/ro A. H. Clark, Proc. U.S. Nat. Mus., vol. 40, 1911, p. 8 (southeastern coast of Africa), 

 p. 43 (description; Providence I., 125 fms.); Crinoids of the Indian Ocean, 1912, p. 233 (synonymy; 

 locality); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 57 (published reference to specimens 

 in the B.M.; locality); Unstalked crinoids of the Srto^o-Exped., 1918, p. 234 (in key; range; 

 references). — Gisi.£n, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, pp. 18, 

 20.— A. H. Clark, John Murray Exped. 1933-34, Sci. Reports, vol. 4, No. 4, 1937, p. 102 (range), 

 p. 104 (listed). 



Diagnostic features. — This species closelj^ resembles P. diomedeae from which it 

 differs in having all the pinnules present, 13 to 15-(- arms, which are 50 to 60 mm. long, 

 in the 4 syntypes and less strongly developed synarthrial tubercles; there are up to 55 

 cirrus segments. 



Description [by A.M.C.]. — The centrodorsal is rounded conical vrith the dorsal 

 pole completely covered with rounded papillae, some of which appro.ximate in diameter 

 to the apical cirri though most are smaller. They rub off ^\-ithout leax-ing any dis- 



